we have a lot of customers with this setup, even putting 600F's on a lot 9X00's and 9X10's
the performance of the 600F head is greatly worth it
yes the 50 series is a little more touchy to set up, but once you have it dialed in, it works great
your 03 will be new enough where it doesn't need a new header control unit, just a software update. you will need a new cornerpost display pad.
then you will either need to decide if you want to switch the head to multi point, or the combine to single point hyd/elec.
level land is real easy as you just get the bolt on hooks for the feeder house, remove the banana castings and install the hooks. you would also want to consider a wedge kit, or at least measure to see how close you are to neeeding one
this may sound like a lot, but i would say that it is definitely worth it